The purpose of this project is: 1) to grow bovine corneal endothelial cells in tissue culture, 2) to repopulate feline corneas lacking endothelium with these cultured endothelial cells, and 3) to transplant these bovine corneal endothelial cell lined corneas into cats using penetrating keratoplasty. Corneal transplants bearing cultured bovine cells elicit a host response that is clinically (slit lamp examination) and morphologically (scanning and transmission electron microscopy) identical to endothelial cell mediated corneal graft rejection. Reports by others suggest that bovine corneal endothelial cells cultured in the presence of exogenous growth factor do not elicit a similar rejection response. A major effort of this project will be to study and identify those factors such as the use of exogenous growth factor, graft repopulating procedures, multiple cell passages, and anti-inflammatory therapy that protect the heterologous cell population (bovine) from the host (feline) response. The success of the grafts will be determined clinically (slit lamp examination, in vivo specular microscopy, pachometry, tonometry) and by correlated morphological (scanning and transmission electron microscopy) methods. Successful corneal transplants will be followed by serial clinical examination to determine the degree to which a heterologous cell population maintains corneal health. An additional corneal homograft series will be conducted in order to better understand the utility of this animal model in the study of human corneal disease. A final portion of this project will study bovine corneal endothelial cell -- feline mononuclear (monocyte, lymphocyte) cell interactions in vitro in order to better understand the immunologic potential of transplanted heterologous corneal endothelial cells.